Fig. 1

Process diagram of SNs and carboxyl content of BS and AS. a Schematic of oxidation and dispersing of silk fiber to silk nanofibers (SNs). b The content of carboxyl groups and weight remaining of water-insoluble fraction after oxidation of Bombyx mori (BS) corresponding to the addition of sodium hypochlorite (NaClO). The carboxyl content increased from 0.293 to 0.889 mM/g BS (NaClO addition was 20 mM/g protein) with 58.52 wt% of protein remaining. c For Antheraea pernyi silk (AS). The carboxyl content increased from 0.347 to 1.013 mM/g AS (NaClO addition was 20 mM/g protein) with 69.30 wt% of protein remaining